The main goal of this research is to understand the molecular mechanics of the "interfacial activation" of soluble phospholipases. We are using NMR and other physical techniques to investigate phospholipid interactions with phospholipase-A2 and phospholipase-C. Specific problems being addressed are: (1) Conformation/orientation changes between monomer and aggregated phospholipid; (2) The physical basis for surface dilution kinetics; (3) The kinetic role (if any) of phospholipase aggregation; and (4) Identification of multiple phospholipid sites in phospholipases.